1. Field of the Invention
This invention relates to a deflection yoke incorporated in such a device as a television receiver or a CRT display unit, and particularly to a deflection yoke which can reduce an unnecessary radiant magnetic field.
2.Description of the Prior Art
In recent years, unnecessary radiant magnetic fields from CRT display units of, for instance, computer terminals, especially an unnecessary radiant magnetic field from a high frequency horizontal deflection coil sometimes affects other terminal units nearby and causes a malfunction thereof, which is a problem to be solved. For this reason, it is strongly desired to reduce an unnecessary radiant magnetic field from the CRT display units.
As a source of the aforesaid unnecessary radiant magnetic field, such devices as a deflection yoke, a flyback transformer, a size coil, a linear coil can be listed, but the main source is a deflection yoke.
Of magnetic fields leaked from the deflection yoke, those other than that in an axial direction of a CRT tube can be shielded, but it is impossible to shield a magnetic field leaked from a CRT face (because the face can not be covered), and so far any effective countermeasure has not been applied to this problem. Recently, it has been tried to offset a leak magnetic field and reduce an unnecessary radiant by adding to a deflection yoke 1 a pair of saddle-shaped horizontal auxiliary coils 13a and 13b (FIG. 14), or a pair of horizontal coil made by winding wire around bobbins respectively 14a and 14b (FIG. 15) to generate a magnetic field which is reverse to the leak magnetic field from the horizontal deflection yoke.
In the conventional technology, however, a saddle-shaped coil or a bobbin-shaped coil is used as a horizontal auxiliary coil, but the coils' form and construction are complicated or a bobbin is required, which causes troubles in manufacturing.
Moreover, to mount a horizontal auxiliary coil to a deflection yoke, a complicated construction of a coil separator is required, and in addition to it the horizontal auxiliary coil largely extends to the outside from a periphery of a front edge opening of the deflection yoke, which also causes a space-related problem.